a. Field of the Invention
The invention relates to time division multiplex communications systems and in particular to a drop-and-insert scheme for such a system.
b. Prior Art
In point-to-point multiplex communications systems, involving serial data transmission, there is frequently a need to provide service to one or more users located along a communications path. Rather than provide separate facilities for such users to one of the points, it has been recognized that it is possible to provide one or more channels for these users which can be added to or subtracted from the system at the user location. These are known as drop-and-insert channels. In time division systems, a typical approach for a drop-and-insert scheme involves decomposition of all or portions of an entire data frame of the main channel consisting of multiple component channels with the accurate phasing of locally generated channels into the data stream.
An object of the invention was to devise a simplified drop-and-insert scheme for a time division multiplex communication system minimizing data processing, throughput delay and hardware complexity.